Do not force using a preset. Do not try to open non-existant preset by default.

Index: transcode-1.1.7/export/export_ffmpeg.c
===================================================================
--- transcode-1.1.7.orig/export/export_ffmpeg.c
+++ transcode-1.1.7/export/export_ffmpeg.c
@@ -1206,7 +1206,7 @@ MOD_init
     lavc_venc_context->me_method = ME_ZERO + lavc_param_vme;
 
 	/* FIXME: transcode itself contains "broken ffmpeg default settings", thus we need to override them! */
-	if (lavc_param_video_preset) {
+	if (lavc_param_video_preset && strcmp(lavc_param_video_preset, "none")) {
 		avcodec_opts[AVMEDIA_TYPE_VIDEO] = lavc_venc_context;
 		video_codec_name = av_strdup(ffmpeg_codec_name(codec->name));
 
Index: transcode-1.1.7/export/ffmpeg_cfg.c
===================================================================
--- transcode-1.1.7.orig/export/ffmpeg_cfg.c
+++ transcode-1.1.7/export/ffmpeg_cfg.c
@@ -124,7 +124,7 @@ int lavc_param_gmc = 0;
 //int lavc_param_atag = 0;
 //int lavc_param_abitrate = 224;
 
-char *lavc_param_video_preset = "medium";
+char *lavc_param_video_preset = "none";
 char *lavc_param_ffmpeg_datadir = "/usr/share/ffmpeg";
 
 TCConfigEntry lavcopts_conf[]={
